The Larynx

The larynx is remarkable for its great length and mobility. The cartilages are more loosely attached to each other than in the other animals. The cricoid cartilage is thick and compressed laterally; its lamina is long and narrow; its arch is directed obliquely downward and backward. The thyroid cartilage is very long; its laminæ are united ventrally and form a median ridge. The anterior cornua being absent, there are no joints formed with the hyoid bone. The posterior cornua are broad, bent inward, and articulate with the cricoid cartilage. The epiglottis is relatively very large, and is more closely attached to the hyoid bone than to the rest of the larynx. The middle part of its base is turned forward, and rests on the thyro-hyoid membrane; it is closely connected with the body of the hyoid bone by the hyo-epiglottic ligament and the strong hyo-epiglottic muscle. The apex of the arytenoid cartilage is very large, and is divided into two parts at its extremity; the inner part is fused with that of the opposite cartilage. There is a small interarytenoid cartilage in the transverse ligament. The rima glottidis is very narrow. The vocal cords are directed obliquely downward and backward; and each is pierced by a long, slit-like opening, which leads into the large laryngeal saccule. The thyro-arytenoid or vocal ligament is similarly divided into a larger anterior and a smaller posterior part. There is a middle ventricle near the base of the epiglottis. The thyro-arytenoid muscle is very strong and is undivided. The arytenoideus is very small. The crico-thyroid consists of two strata; the superficial layer corresponds to the muscle of the other animals; the deep part consists of transverse fibers.